What is a PET/CT Scan?
A PET/CT scan combines two imaging techniques: Positron Emission Tomography (PET) and Computerised Tomography (CT). PET produces 3-D images of your body and allows us to look at your metabolism and other important functions. We can also study any changes that are happening over time while we monitor your condition. The CT scan uses computer-processed X-ray measurements to create a detailed image.
How does it work?
Before carrying out a PET/CT scan, a ‘tracer’ (a type of radioactive substance) will be injected in to your arm, hand, or foot. The tracer spreads through the body and gives off a type of radiation that shows up on the PET scan. This allows the scanner to build up a detailed image that identifies areas of the body affected by disease, as well as some of the body’s functions.
The PET scans are combined with CT scans which adds the precision of anatomic localisation to functional imaging enabling a more accurate diagnosis. The CT scanner takes a series of cross-sectional images (‘slices’) and then computer processing is used to construct a three-dimensional image.
Having a PET/CT scan
A radiographer will ask you to lie on the scanner bed and make you as comfortable as possible. The scanner bed will move gently and slide you into the centre of the scanner until the part of the body to be scanned is correctly positioned. While the scan is taking place, you’ll need to remain still.
The scan takes between 20 and 45 minutes but there’s also some preparation time, so you’ll need to allow about two hours for the appointment.
The amount of radioactivity injected in the tracer is relatively small and will be excreted by your kidneys (passed when you urinate). It will not produce any side effects. You can eat, drink and travel as normal after the test. However, as a precaution, we advise our patients to avoid having close contact with young children and pregnant women for 4 – 6 hours after leaving the department.
The test is not advised if you are pregnant or are breast feeding.